There are a number of compounds which make up butter flavor and aroma. Probably the most important group of compounds are the lower carboxylic acids such as acetic, propionic, butyric and caproic acids. Other important components of butter flavor include the methyl ketones and lactones. See U.S. Pat. No. 2,819,169 to Boldingh, issued Jan. 7, 1958 which discloses that the lactones, especially the gamma variety, impart butter-like flavors to oleaginous compositions.
Another important component of butter aroma is the compound diacetyl (2,3-butanedione). This compound is a yellow liquid having an extremely potent butter aroma. Diacetyl can be formed via two different methods. The first method involves chemical synthesis. For example, diacetyl can be synthesized from methyl ethyl ketone by conversion to an isonitroso compound which is then decomposed by hydrolysis with hydrochloric acid to diacetyl. See the Merck Index (8th Ed. 1968), page 337.
A second method for producing diacetyl is by bacterial fermentation. For example, glucose can be fermented to methylacetylcarbinol which is then oxidized to form diacetyl. See the Merck Index (8th Ed. 1968), page 337. See also U.S. Pat. No. 2,586,072 to Marcoux, issued Feb. 19, 1952 which discloses production of diacetyl from a bacterial culture such as S. diacetylactis incubated at temperatures of from 70.degree. to 80.degree. F. until titratable acidity of 0.55% lactic acid is present. A method which would increase the diacetyl production of a bacterial culture would therefore be desirable.
It is therefore an object of the present invention to provide a bacterial diacetyl-producing composition.
It is yet a further object of the present invention to provide a method for increasing the diacetyl production of diacetyl-producing bacteria.
These and further objects of the present invention are hereinafter disclosed.